In-Hospital Outcomes of COVID-19 Associated Myocarditis (from a Nationwide Inpatient Sample Database Study)

The prevalence of COVID-19 infection-related myocarditis, its in-hospital cardiovascular outcomes, and its impact on hospital cost and stay at national level are not well studied in the literature. The Nationwide Inpatient Sample Database from 2020 was queried to identify patients with COVID-19 and myocarditis versus those without myocarditis. Cardiovascular outcomes and resource utilization were studied among cohorts with COVID-19, with and without myocarditis, using descriptive statistics, multivariate regression matching, and propensity score matching using STATA version 17. Of 1,678,995 patients, 3,565 (0.21%) had COVID-19 with myocarditis, and 1,675,355 (99.78%) had COVID-19 without myocarditis. On multivariate regression analysis, we found higher odds of in-hospital mortality (adjusted odds ratio [aOR] 1.59, 95% confidence interval [CI] 1.27 to 1.9) in patients with myocarditis than in those without myocarditis, in addition to higher odds of major adverse cardiovascular and cerebrovascular events (aOR 3.54, 95% CI 2.8 to 4.4), acute kidney injury (aOR 1.29, 95% CI 1.27 to 1.9), heart failure (aOR 2.77, 95% CI 2.3 to 3.4), cardiogenic shock (aOR 10.2, 95% CI 7.9 to 13), myocardial infarction (aOR 5.74, 95% CI 4.5 to 7.3), and use of mechanical circulatory support (aOR 2.81, 95% CI 1.6 to 4.9). The propensity-matched cohort also favored similar outcomes. In conclusion, patients with COVID-19 and myocarditis had worse clinical outcomes, having a higher rate of in-hospital mortality, major adverse cardiovascular and cerebrovascular events with longer length of hospital stay, and higher hospitalization costs. Large prospective trials are necessary to validate these findings with diagnostic measures, including biopsy and cardiac magnetic resonance imaging for the extent of myocardial involvement.